Prison staff may take some solace in the positive review they received.

“The staff are pleasant enough,” wrote Willoughby.

Humberside police is treating the incident as a security breach.

The mystery as to how the suspect managed to smuggle his tablet into the cell is under investigation.

Humberside Police Chief Inspector James Glansfield said: “These appear to have be taken by a prisoner while in custody on Wednesday 9 March.

“We take any such breach of security and detainee safety extremely seriously and will be carrying out a review of our detainee management to identify any lessons learned and prevent further reoccurrences in the future.”